Congress requested that GAO examine: (1) whether DOD has defined hybrid warfare and how hybrid warfare differs from other types of warfare and (2) the extent to which DOD is considering the implications of hybrid warfare in its overarching strategic planning documents.

GAO found that DOD has not officially defined hybrid warfare at this time and has no plans to do so because DOD does not consider it a new form of warfare. Rather, officials from OSD, the Joint Staff, the four military services, and U.S. Joint Forces Command told us that their use of the term hybrid warfare describes the increasing complexity of future conflicts as well as the nature of the threat.

Moreover, the DOD organizations we met with differed on their descriptions of hybrid warfare. For example, according to Air Force officials, hybrid warfare is a potent, complex variation of irregular warfare. U.S. Special Operations Command officials, though, do not use the term hybrid warfare, stating that current doctrine on traditional and irregular warfare is sufficient to describe the current and future operational environment.

Although hybrid warfare is not an official term, we found references to "hybrid" and hybrid-related concepts in some DOD strategic planning documents; however, "hybrid warfare" has not been incorporated into DOD doctrine. For example, according to OSD officials, hybrid was used in the 2010 Quadrennial Defense Review Report to draw attention to the increasing complexity of future conflicts and the need for adaptable, resilient U.S. forces, and not to introduce a new form of warfare.

The military services and U.S. Joint Forces Command also use the term "hybrid" in some of their strategic planning documents to articulate how each is addressing current and future threats, such as the cyber threat; however, the term full spectrum often is used in addition to or in lieu of hybrid.